It was sent by the Stevens collusion enquiry team and concerned a complaint it had received from Mr McCord's father, Raymond Snr.

Mr McCord Snr today said details of the letter should be made public.

"I want to know what actions the RUC took in 2000 about the allegations I made at that time," he commented.

"I welcome these freedom of information requests and hope they will help establish the full facts."

The 1997 McCord murder by a north Belfast UVF gang was the starting point for a devastating report issued last week by Police Ombudsman Nuala O'Loan.

It linked a prime suspect for this killing, Mark Haddock, to at least nine other murders.

It also stated that Haddock remained a paid police informer until 2003 - three years after the Stevens team wrote to the RUC chief constable.

The existence of correspondence between Stevens' investigators and Sir Ronnie's private office was confirmed to this newspaper last week by the PSNI.

A spokesman for the force said: "The matter was outside the terms of reference of the Stevens Investigation and was therefore sent to the RUC.

"The letter was sent to the investigating officer responsible for the case and it was included as part of their investigation at that time."

Sir Ronnie is now head of Head of Her Majesty's Inspectorate of Constabulary, which oversees all UK police forces.

He rejected criticism following last week's O'Loan report and stated: " With respect to the specific matters dealt with in the Ombudsman's report, at no time did I have any knowledge, or evidence, of officers at any level behaving in the ways that have been described."

Speaking in the Commons, SDLP leader Mark Durkan accused Sir Ronnie of presiding over a culture of 'anything goes but nobody knows' in the RUC.

The former chief constable has not responded to a Belfast Telegraph query about the Stevens team letter.

A freedom of information request on the correspondence has now been submitted by this newspaper to the PSNI. It's understood a similar request has been made by the SDLP.